This invention relates to a method for feeding rod-like workpieces in a severing machine, such as a frame saw, a cold circular saw, a band-saw or the like. The material supported on the machine bench of the saw machine stand and on a feed device upstream of the machine bench as viewed in the feed direction, is clamped in the zone of the cutting plane during cutting between at least two clamping jaws which are openable and closable transversely of the feed direction and two feed jaws. The feed between the cutting operations is effected by the feed jaws which are openable and closable transversely of the feed direction and may be displaceable by automatic control along the feed direction. The feed jaws open after the execution of the cut, then grasp the material anew and advance it while the clamping jaws are open. The invention also relates to an apparatus for performing the novel method.
In prior art arrangements the clamping jaws are divided or have an incision in the zone of the cutting plane of the saw blade for grasping the workpiece on both sides of the cutting plane. In this case the workpiece feed is effected by opening the feed jaws arranged on the feed side of the material after the execution of a cut, so that they can travel back a distance by which the workpiece is to be advanced anew. At the same time, the leading end of the workpiece is held by that part of the clamping jaws which is situated on the feed side. There the feed jaws grasp the material again and advance it while the clamping jaws are open. Thereafter the clamping jaws close again, whereupon the next cut begins.
In the above-outlined known rod feed, which in most cases is set in a control device and thereafter works automatically in cycles, one of the problems consists in keeping the residual length of the workpiece remaining after the severing operations as short as possible, in order to prevent excessive material waste. In the known arrangements as explained above, the minimum residual length is determined by that part of the clamping jaws which is situated on the feed side and by a minimum length which suffices for being grasped securely by the feed jaws. In this connection it is a further difficulty that if the residual length is short, upstream of the clamping jaws the workpiece has no longer any secure support.
To reduce the residual length, it is known to provide that part of the clamping jaws which is situated on the feed side, with a recess into which the feed jaws can enter and thus advance more closely to the cutting plane. In this case too, however, the residual length is considerable and is frequently greater than the length to be cut off according to the program. Thus, a waste length is obtained from which at least one more useful length could still have been cut off.
In the prior art structures it is a further difficulty to sort out the residual workpiece length and the initial cut from the next succeeding workpiece from the pieces cut off in accordance with the program. In case of a normal feed, the residual length and the initial cut are situated in the feed path between the normally severed parts, so that special measures are necessary to sort them out.
In addition, when a known severing machine is used, special measures are required to link the machine with afterconnected machines for the further processing of the severed lengths. The latter emerge from the severing machine by being pushed by the upstream-located severed lengths. The severed workpieces are otherwise unguided and thus special guide arrangements have been necessary for the appropriate handling of short and long lengths, on the one hand, and for feeding the severed lengths to further processing stations, on the other hand.